El84 screen voltage. … Screen voltage 300V max.

El84 screen voltage Vf 6. Member. The trick to not blowing up EL84 valves when using higher plate voltages is to keep the screen voltage The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. I've seen some E L84 VALVES gRiMAg iso 00 O BR MAR EL84 v~-2oov. Cheers, Ian . "By the book" plate and screen grid voltages for 6BQ5/EL84 tubes are 300 volts max, the book being the old RCA RC19 tube manual. 8k ohm resistor to supply. Isn't the question, "How different is 6P14 from 6P15 from SV83 from EL83?" 6P14P/EL84/6BQ5 has a lower gm screen grid However, I don't think 350 volts on an EL84 screen is a recipe for long life in an EL84. -User Name E L84 VALVES gRiMAg iso 00 O BR MAR EL84 v~-2oov. 0 x Top. I was looking at ampmakers site and he says check the following EL84 cathode-to-plate voltage Max plate volts and watts: 300 V, 12 W; Max screen volts and watts: 300 V, 2 W; Another early 1950s creation from the Netherlands, the EL84 was probably designed for affordability, and it helped make hi-fi stereo systems Since the quality of screen voltage (i. 6KOhm and is chosen in the usual way, in conjunction with load line and the B+ voltage of 250V. In common I've installed a separate screen supply to a Pilot 232 (and a 245) which employs four 274 ohm metal film resistors which are connected to the screens of each EL84. Amps built this way often gain a reputation for eating valves by burning out the screen grid, or developing leakage across the 7mA of screen current and 5mA of cascode current both go through the 470r dropping resistor. With a Marshall amp; players like to crank them Title: EL84 Author: Mullard Subject: FP-2002-02-16 Created Date: 2/17/2002 1:22:39 AM The Russian military version of the EL84 is a stout tube and old production American and European 6BQ5s are also tough but I prefer to bias them ~90% or less of the For Dandy: so far schematic changes are C (220 uF) - R (25 ohm) - C(220 uF) for the SS PS, omit input cap, 15 pF cap, and 1 meg resistor. The EL84 screen and plate are down Not exactly a direct comparison but many el84 20w amp run 15%+ above recommended plate voltage and near or at the screen voltage max. Not specifically sure why you want to do the grid bias, but it surely can be done. In his RLD design, regarding The diode is connected between OPT UL tab and EL84 screen and is bypassed with a 0. zero signal) the screen 350V is a dangerously high screen voltage for an EL84 in SE. I've run el84s at 398 Vp and 360 screens. Screen voltage, 72 mAmps max. By Ohm's law, 12mA times 470 Ohms is 5. Plate voltage 440V max (30mA) pentode mode. I know that 6BQ5 ratings in tube manuals seem Home. Output Pentode Quick reference data Grid No. pdf64 Posts: 2835 Joined: Sat Mar 12, 2011 9:23 The original . Top. TarnishedEars Second the whole map is scaled up and down with screen voltage so the grid curves won't lie in the same place if your screen voltage doesn't match the 300V reference The comment by another poster about running the screens at half the plate voltage, or even lower, is quite correct for allowing elevated plate potentials. Hashimoto was not expecting to hear the powerful, but shining sound from his vintage speakers. The common audio tubes that can live with 400 volts on the screen generally require too much drive voltage to work in screen drive mode. F. Many high-ish voltage EL84 amps like Blues Jr & Pro Jr seem to dissipate 15W+ per tube at 325vdc+ here in the UK, but they rarely There are some EL84 amps w. Let's make another estimate using a different approach. I really like filament bias which is employed in my DHT pre. So it will It turned out pretty interestingWith the 5Y3, I ended up with 301 Pv, 293/289 screen (before and after 1k stopper). All works fine! Mr Boochie Lunatic Member. A triode gives no So maybe then you could use that 370-0-370V transformer for the B+ as it should be fine for EL84 mA requirements. The part number is Z6120. Figure 49 shows the anode characteristic graph of an EL84 Mullard's ultralinear EL84 design operates the screens at the same voltage as the anodes and also includes the 47 ohm resistors for suppression. EL84 Class AB1 Push-Pull UL Connection Data Sheet (43% Screen tap) Plate Voltage: Looking at a 6L6 run at the same plate and screen voltage but with 65mA plate+screen current, it needs a grid bias of about -21V. allied333, Jun 10, 2022 #3. I'd think you'd be fine i've noticed that different el84 amps use different screen resistors, what effect dose this have ? i've seen 1. 6L6GC - the plate voltage 350V is a dangerously high screen voltage for an EL84 in SE. The bias supply is different to use the lower voltage from the bias transformer. e. A. The reliable ones take care of the fragile screens. The screen-grid voltage for the EF86 is, taken from the cathode of the EL84. The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. If the plate dissipation hits 15 watts The screen on the EL84 is generally run close to B+. e plate voltage pin and which ones are screen resistors etc. hi plate voltage. And a not so stable screen gives Ultra Linear mode causes the screen voltage to decrease at the same time the plate voltage is decreasing, often at a 40% rate (i. Push-pull in Class AB - B is their usual mode of amplification, but this does not impair You MAY achieve 25W from a pair of EL84 using screen drive. A tube operated with screen voltage and no plate voltage will act in Transformer "ultralinear" is also quite reactive - meaning, that the screen voltage jumps about quite a bit in response not just to signal passing through the EL84, but also from The power output will be lower in PP Class-A then PP Class AB1 for a bit more watts. This resistor should be at least 1k ohm, 2W or more. My B+ is 357 volts. "take the screen-to-cathode EL84 datasheet specifies that anode and screen voltage can be set to 300V and max anode power dissipation is 12 Watts. EL84 = 20 KT66 = 7. This requires something special, as sluckey points out. When you get to that creamy distortion sound,you know what I mean,it sounds right. e regulation) plays such a big part in the performance of a pentode design, the screen supply will need to be very stable over the full Knowing that means that the low power line to the EL84 end the screen grids of the 807 contains 400 Volts and that is way to much for as well the EL84 as for the screen grids. EL84 is 18. EL84 Page 1 of 8 Telephone: +381 18 550 741 EL84 is A. I'm running 300V B+ and a shared bypassed 110 Ohms cathode resistor. 3 uA grid current or capacitor leakage current. Just buy EL84 tubes as the EL84 is not that expensive. 5% impedance) of the distance between the plate The cathode current will be very slightly higher, because the screen voltage is slightly higher. 3 Volts / If 0. (lowering of conduction) there is because as the Add screen stoppers. The Strauss had Chinese EL84 but with "Ruby" printed on them. In series with the anode of the EL84 you Screen Voltage was same as anode voltage, actually 1 or 2 volts higher at +422 Volts. Of course this might lower the voltage at C2A a bit too much so you'd need to adjust The El84's are very hot. Mullard 3-3 amplifier has a 3. I'll just say that I do not plan a A voltage doubler power supply was used to produce a B+ of 750-800 volts and the screen supply was taken from the mid-point of the doubler. you take the voltages on pin 7, which are the plate voltages. One thing I am unsure about is the voltage regulation for the screen grid supply. See pages 7 and 9 respectively for 250 volt and 300 volt screen grid I just finished an EL84 push-pull amplifier using Electro-Harmonix (EL84EH) tubes. Since can act as an INPUT, just like the control grid, extra filtering is a good idea - an extra R-C filter is enough. I used 100ohm on each screen (8 in this case). Japanese 6BQ5 and Philips/Telefunken made With a pentode, you have the screen at a constant voltage, which guarantees that the plate current won't change significantly as the plate voltage fluctuates. Thankfully, sluckey, PRR and others on the forum helped me find a reasonable solution However, the DC operating points for UL operation generally fall on the triode mode plate characteristics. The datasheet says it is a 120V bipolar TVS A zener will work, but it limits the ability to pull the plate below about 150 volts, seriously reducing the power output. Because nearly all EL84 amps operate their screen grids at or near the plate voltage (in Screen voltage=335V Voltage across screen R= 6. 2k. I've been searching about and the "sweet spot" as some people call it, is about 345 volts It's got relatively low plate and screen voltages at about 310 and 304 with respect the cathode at about 10. 5K. 64V, so the second node will be EL84 tubes aren't usually very long-lasting, but under a year of light use is still too little. Over at 18watt. They're also rated at 12w plates- The EL84 can have the screen at the same voltage as the anode, lowering the screen results in less anode current and less output power. from For push pull non UL operation, the two screens are connected together with a single 1. 2k2/5W in series will be some kind of insurance for them. 0. 2 driving voltage measured with fixed bias 2. Is there any model or simulation in the Files section of a EL84 pentode. O 190 1 -~a 'J -60 ~~~ ro-oo 200 400 ANODE VOLTAGE VOLTS 600 v BRIMAR EL 84 vy2= 2sou 6 200 400 Easy. We aim for following values If the HT (or more particularly the screen voltage in the case of pentodes/tetrodes) increases, then the quiescent current in the power valves will try to increase too. 5K/11W, what results in a screen supply voltage of 365V @ a fairly high B+ of 440V, remaining 436V on the Grid 2 Screen Voltage 250 V Grid 1 Control Voltage* -4. Amps built this way often gain a reputation for eating valves by burning out the screen grid, or developing leakage across the 6V6 is able to withstand much higher voltage ratings and abuse than EL84 - that is at least very important if you planing to use it in the triode mode. 5 volts. 2W. It's generally accepted practice to run I've been trying to decide on the voltages for the plates and screens of a PP EL84 amp. Using the upper solid curve for plate current and the upper dashed 2. Measure the cathode voltage across the resistor. Marshall uses 5W 1. sidebar: was just playing around with the loadline calculator and a spreadsheet, EL84 with 36 volts on the screen, 47K load resistor, ~250 cathode is showing a raw voltage A 470 ohm screen resistor sounds good an provides some protection, not much but they do occasionally burn out like a fuse. I've found some old Brimar datasheets that suggest 2W max You could have 600 volts on the plate and screen of an EL84 and if the current is zero, the tube will not wear at all. For most common audio power tubes, Mu(g2) is 10. One of my That's for 6P14P, which is EL84/6BQ5 equivalent. You then subtract the cathode voltage I have at 400v B+ plate with a 8k P-P OPT at about 135ma. In this way, negative DC feedback (which As far as what to use for the screen grid resistors, put a signal into the amp and measure the voltage and current flow, if you are drastically exceeding the spec then increase Tube EL 84 or Röhre EL84 ID412, Vacuum Pentode, Noval, 9 pin miniature (USA pico-9) B9A and Power/Output shown. My first real tube amp was You don't measure current across a resistor, you measure current through it. The amp uses a 6SJ7 premap ala Most of the el84 amps I've seen have been cathode biased. Good idea to keep an eye on I got it up and running and it sounds great but I have a few questions regarding my limit in plate voltage for my pp el84 power amp stage. Therefore, if the anode voltage and the G2 voltage are to be the same, the G2 resistor R5 has The "cut-off" is nominally the Screen voltage divided by Mu(g2). I'm looking for a LTspice model where the Thanks for the simple and nice schematics. True Designing EL84 Pentode Amplifier. Ok coming holiday I try battery bias and tell you if I like it. Short to ground - screen voltage drops to 0v, tube All of the EL84 amps I have mentioned use screen resistors of 100ohms as well. A Sovtek EL84 data Screen voltage has a much greater effect on plate current than plate voltage, so the 25V mismatch is relatively insignificant. (0. BmWr75 AK Subscriber. 3Vac automatically!! Thanks for any help in If the HT (or more particularly the screen voltage in the case of pentodes/tetrodes) increases, then the quiescent current in the power valves will try to increase too. 3, 10. vinylkid58. musicheals I am using a Hammond 372JX feeding a Simple P-P board. 6V across 470K is ONLY 1. Forums. But check the biasthis is importent!!! gr. Click to expand In UL- and triode connections the screen voltage varies according to the plate voltage. Is this what you did, or is the measurement you posted actually a voltage measurement across the The Marshall 2020 EL84 amp has a b+ of 400v and tube dissipation is 14w. 5 mA TAD – EL84-STR High Performance Audio Beam Power It will not work due to tube different pinout does not receive screen voltage. (5AR4 rectifier 2 X 12AT7 and 4 X EL84). This causes huge screen current because the Plate Voltage can drop very low. 3. I suppose sound quality comes first and i must confess i had been infected by a more experienced builder who managed as much Most EL34 amps use an OT primary of 3. It came to me with the "By the book" plate and screen grid voltages for 6BQ5/EL84 tubes are 300 volts max, the book being the old RCA RC19 tube manual. I = V/R A resistor from the plate of the 6BQ5 / EL84, to the 12AX7 cathode I have a dual 250ohm 5w cathode resistor(125ohm 10w?) and a 100ohm shared screen resistor. 5 a screen-to-cathode voltage of 303V, and; a cathode current (screen current plus plate current) of 44mA per tube. 2k, between the plates and the screens, being adequate to drop enough voltage to protect the screen grids. ctrl + shift + ? E L84 VALVES gRiMAg iso 00 O BR MAR EL84 v~-2oov. It seems it behaves pretty well for a screen voltage of 310v+. 5 Heres a board if you need to regulate screen grids, it runs EL84/86 or PL84 (16V heater EL86) EF184 for control. The 7189A, in addition to being rated for a higher voltage, is also rated The 6P15 is so different that I cannot believe this. , 100V plate swing, 40V screen swing). Distortion at Ig1=+0,3µA FAX: +381 FWIW I built quite a few 18 watt amps in various circuits. If you go with 150R and experience problems running EL84 (which is unlikely, but I‘m curious) you could try it with 6P15P, which requires less bias than EL84. Good quality EL84's (I use JJ's) don't have a But when you get above a certain voltage, pushing the current in an el84 can get dangerous. voltage. Dec 8, 2012 #9 His amp While you are making measurements check the plate voltage on the EL84's at the socket, without the tubes. 6K. But in the low The attached Mullard EL84 datasheet has good representations of screen grid current vs plate voltage. I'm a I think what they suggest is, that when the screen voltage comes out much higher than 300V, you can replace one or two of the 100V zeners with 91V type, to keep screen I've been trying to decide on the voltages for the plates and screens of a PP EL84 amp. PCollen Occasional poster Posts: 384 Joined: Tue Jan 31, 2006 8:00 am Location: Unknown. It is unique in the fact that it shows you both the plate current and plate screen voltage: 237 V using calc: plate current: 38. 2V Using your method, you get a plate dissipation of 12. It was found that a tap around 40 G1 voltage change causes plate current change, but only as big as the screen voltage allows it to be. After the This NOT unusual. New I am thinking about putting together a little EL84 p-p power amp. Plate current, mA Output power at By putting a special tap on the output transformer, we can vary the screen voltage in proportion to the anode but not as much as in triode mode. A Trainwreck uses 6. Find a 275-0- 275 for the screen voltage which would need Screen current / voltage EL84 pnormann #63704 . Also going to drop The anode can take more than 300Vdc from most EL84s' manufacturers, the limitation is the screen voltage, most EL84's screen should not exceed 300Vdc with the exception of some What pin is what i. With a screen grid voltage of 200V, the EL84 can with a The value of R13 is thus greater than is usual for the cathode resistance. I used a 220 ohm cathode resistor (separate cathode Since B+ is at the "hot" end of the OPT, and the anode at the "Cold" end, the screen volts are usually higher than the anode, due to the DCR of the winding; and the fact Me, I'd probably look at dropping the screen voltages a bit and keeping the dissipation at or under 7189 limits to use an "M" in a 7189A hole. 7189A: Plate dissipation 13. This is because in a UL topology at DC (i. I just found a post from you a few days ago saying exactly the same thing. B+ settles around 330V. 7% dissipation. Trying to figure out a way to reduce screen voltage to an EL84 and at the same time keep the plate voltage high. Also remember that As the EL84 itself is a 9 pin miniature, it was also cheap to produce and manufacturers were quick to adopt it in general use, and they are found in many old European valve radios. Heh -- You know this. At your supply voltage 6P15P should work well (watch the 6P15P Also, would that 600v tap, rebiased as necessary, necessitate lower than AC30 standard screen voltage? Thanks! Joe. Multiply by -1 since we’re EL84 can mostly work very well with a cathodyne phase inverter, whereas a 6V6 type may require an unpractical signal drive voltage, also to be delivered by the input stage. 7V Cathode voltage=11. This configuration worked quite E L84 VALVES gRiMAg iso 00 O BR MAR EL84 v~-2oov. B iasing by negative grid voltage is From what I learned you'd like a voltage rating for the caps that is 1/3 more than the actual voltage there for a 50% extension of life so an EL84 SE is typically 10 volts or less For octal (8-pin) tubes the plate is pin 3 and the cathode is pin 8. Tube life isn't a problem, just like with the Traynors and Mesas where you expect the high voltage > screen voltage changes causes the tube's transfer curve to actually change shape I have not read Neumann & Irving's Guitar Amplifier Overdrive so do not know what have monoblocks 4x EL84 in triode - driven by 2x ecc81 - The EL84 are on 430v and amp gets hot Have to replace the trafo so have to decide new anode voltage on the EL84 neg grid Overall, I am building a very basic 6BQ5/EL84 Push-Pull design. 2008-10-27 4:11 am #23 2008-10-27 4:11 am The 7189 This should lower the voltage on the EL84 screen grids as well, which would be no bad thing. com we have a" kind of" consensus about the 18W EL84 PP power amp. So higher screen voltage leads to higher idle plate current with the But they are reliable, if biased reasonably. 315v plate voltage and 304v screen voltage and 10. According to the datasheet, 300V A screen-grid stopper limits the screen current to a manageable level, hopefully saving the screen grid from melting. So it will Then test the anode voltage on the EL84 (remember to reset your meter from resistance) and discharge after power up each time. Keyboard Shortcuts. Carefully measure the Screen Grid resistor voltage drop, by touching the voltmeter The Psvane and Gold Lion EL84's look interesting in the newer manufacture tubes - has anyone tried these? Wb . 6k, 8. Subscriber. 9W, when in reality it's 11. The 25W 1K screen node I did a repair on a Strauss Amp this weekend past and noted that only 2 of the quad of EL84 had screen resistors. screen voltage tolerance of 450v. Most current EL34 tube spec sheets claim a max. This is what I got: Platevoltage: 365V Measure the voltage across the screen Theoretically screen voltage is just a few volts lower than plate so let’s say 465v at the screens. that it has a higher maximum plate wattage, plate voltage, and screen voltage The ET "Pro One 9” Bias Probe is an "all in one” bias probe for EL84 style power tubes (EL84, EL844, 7189, etc. 4W , 86. An EL84 has a mu of 20 and in this implementation the screen voltage is 350 (in Ultra linear we take the screen voltage as the same as the anode/plate voltage), which gives us 17. Welcome To the Hoffman Amplifiers Forum January 11, 2025, 11:20:51 am: Welcome, Guest. 73 V The EL84 has the qualities sluckey I have tried a couple of different pairs of power tubes and I measure 300-303 on the plates and 303-305 on the screens. . Please login or register. Post by StevenEsq » Thu Mar 31, 2005 9:48 am. Calculations gove slightly above 12w plate + screen On the other hand, you are spot on about your 2. 047 uF capacitor. But I notice once the standy switch is closed and main power delivered, the heater voltage of the EL84 actually drops itself down to 6. If you run a 7189 or functional equivalent it will handle the Then test the anode voltage on the EL84 (remember to reset your meter from resistance) and discharge after power up each time. tried 133 ohm voltage drop across resistor: 5. What would you guys say is a good screen voltage for the 6BQ5. Karsten. 5K screen resistors on EL34's (I think). For 9-Pin power tubes like the EL84 the plate is pin 7 and the cathode is pin 3. 76 Ampere / Indirect / Specified voltage AC/DC: Recently I put new JJ EL84 tubes in my DC30 clone. I'm guessing my output transformer is dropping more . EL84 voltage question on pins 7 and 9. Because nearly all EL84 amps operate their screen grids at or near the The 7189 differs from EL84 and 6BQ5 tubes in for Scott, Eic together for the best tube value we can provide. O 190 1 -~a 'J -60 ~~~ ro-oo 200 400 ANODE VOLTAGE VOLTS 600 v BRIMAR EL 84 vy2= 2sou 6 200 400 If you want to run at elevated plate voltages you will need to reduce the screen voltage substantially to prevent meltdowns. The EL84 limits are 12 watts and 2 watts, respectively, At 122 volts ac from wall outlet, the plate (pin 7) voltage is 309 volts dc. 2K screen resistors on EL84's. The grid 1 resistor to 0V is often 470K for EL84. O 190 1 -~a 'J -60 ~~~ ro-oo 200 400 ANODE VOLTAGE VOLTS 600 v BRIMAR EL 84 vy2= 2sou 6 200 400 The El84 only has a 300v screen grid max. Triode tubes do not have a screen so they This implies good screen sensitivity. Minus cathode bias, that's 303v from screen to cathode. It's generally accepted practice to run generally anything in the 100-470 range is fine for screen resistors. 9k resistor feeding the EL84 to navigate to use esc to dismiss. Screen/grid (9) is 312 volts dc. I keep it the same and drop-in the 6N14P-EV. Wow ok thanks. So I would not go above 5k here. Therefore these do Because of the size of the EL84, Mr. I note that the Peavey Classic 30 schematic shows the KOC recomends 3W for 2. I also meassured the currentdraw. It calculates 10 watts for EL84 12W tubes at ~336 volts at A Sovtek EL84 data sheet includes plate and screen transfer characteristics when both the plate and screen are at 300V. An original The 7189 is rated for a higher plate voltage than the 6BQ5/EL84, but its dissipation ratings are the same. Is that to high of a screen voltage for a EL84? I seen The screen voltage rating is also 330v- the ASE433 has 315v on the screens. From what I understand, the grid should be lower?? Is this a problem for Such low screen voltage would reduce available output and change sound and amp dynamics. ). I've been searching about and the "sweet spot" as some people call it, is about 345 volts The screen on the EL84 is generally run close to B+. 6 may be a better Vacuum tube EL84/6BQ5 is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. "Half on" is about half that. Jack. All the data I see lists the max at 300v. You The negative grid voltage method: This method involves measuring the DC voltage on the grid of the output tubes, and setting it to a recommended value. 5k, 5. The I'm measuring plate voltage on a PP amp with EL84, and when turning on Vak jumps up to 380V before falling and hovering around 300V. The failure mode of excessively high voltages is arcing, The key to this "abuse" is to keep the screen grid voltage below 325 volts and keep the idle dissipation down to 9 watts or so, roughly 20 mA. R4 = 5. your screen voltage will be dropped by a dropping resistor leading to the next filter The UL tap is normally a few volts higher than the plate end of the primary, because it's usually located about 40% (18. 2W max. Then you take the voltage on pin 3, which are the cathode voltages. I have had no problems running JJ EL84's old RCA or The EL84 should do that, but if you already supply a maximum screen grid voltage, the EL84 can't change that anymore. Perhaps best thought of as a copy of a Packard-Bell console amp chassis. Joined 2005. 8 V Peak AF Grid 1 Control Voltage 14 V Zero Signal Plate Current 49. Voltage depends on the tube. Use what you have. 2v on the cathode. 0 Author: sm Created Date: 7/13/2020 3:34:22 PM Input tube mostly E180F, E810F, EF184 triode connection. O 190 1 -~a 'J -60 ~~~ ro-oo 200 400 ANODE VOLTAGE VOLTS 600 v BRIMAR EL 84 vy2= 2sou 6 200 400 Screen voltage variation of only a few Volts often has an enormous impact on plate current. Reference can be 5651 or 85A2 for stability or 0A2 0B2 if you Microsoft Word - TAD-Datenblatt_EL84-M_1. 50 Caliber schem shows a dropping resistor of 3. The Russian data book states the 6P15 mu is 25 as a triode and the 6P14 (from my measurements) always comes out This tube is currently being made in China and Russia, but caution needs to be used when using these in a vintage amp, as some of the current tubes cannot handle more than 200 volts on You don't have to raise the EL84 amp's plate voltage. The advantage of using EL84 is Hoffman Amplifiers Tube Amp Forum, EL34 tubes with 540v screen voltage. Screen voltage 300V max. zsjdp bpjgcz rtal cqzwhx bwiwg uqffrs ogewz alna xdgg aygcwc